Helix AMPLIFY 204 X-OVER – compact 4-channel amplifier with active crossover
The AMPLIFY 204 X-OVER is part of the HELIX AMPLIFY 2-Series, a family of specialized amplifiers – from 6-channel full-range models to mono subwoofer amplifiers – offered in DIRECT, X-OVER and DSP variants. The 204 X-OVER provides four fully bridgeable channels for a 4-channel system, 3 channels plus subwoofer, or a bridged 2-channel setup, and is aimed at upgrading factory or aftermarket head units.
Its integrated active crossover with adjustable high-pass and low-pass filters supports active front systems with separate tweeter and woofer channels, passive front and rear systems, or a front system with a subwoofer on bridged channels. Switchable highlevel and RCA inputs, a smart highlevel input with ADEP.3 for communication with factory radios and an automatic turn-on function simplify installation, while the DirectDSP function passes the signal unfiltered to the output stage when an external DSP is used.
Key Features
- Four Class D channels: 4 x 100 W RMS at 4 Ohm or 4 x 190 W at 2 Ohm; up to 240 W RMS per channel at 2 Ohm (one channel driven).
- Fully bridgeable: 2 x 380 W RMS bridged at 4 Ohm for 4.0, 3.1 or bridged 2-channel layouts.
- Active crossover: high-pass and low-pass adjustable from 45 to 400 Hz, 12 dB/oct, each can be switched off.
- Switchable highlevel/RCA inputs: up to 16 V highlevel input sensitivity.
- Smart highlevel input with ADEP.3: for communication with OEM systems and factory radios.
- Automatic turn-on: via the highlevel input, reducing installation effort.
- DirectDSP function: bypasses the internal crossover and feeds the signal unfiltered to the output stage.
- Input mode switch: to match the input configuration.
- Start-stop capability: uninterrupted operation down to 6 V supply voltage.
- Compact, efficient design: Class D with low heat dissipation, SMD hardware, removable top cover and matte finish.
Inputs & Outputs
- 4 x RCA inputs, sensitivity 1–8 V, input impedance 8 kOhm
- or 4 x highlevel speaker inputs, sensitivity 2–16 V, input impedance 9–33 Ohm, with ADEP.3 and automatic turn-on
- 1 x remote input
- 4 x speaker outputs
Power & Amplifier Section
- 4 x 100 W RMS at 4 Ohm, 4 x 190 W RMS at 2 Ohm, 2 x 380 W RMS bridged at 4 Ohm (≤1% THD+N at 14.4 V)
- Max. output (one channel driven, ≤10% THD+N at 14.4 V): up to 240 W RMS at 2 Ohm, up to 480 W RMS bridged at 4 Ohm
- Class D amplifier technology
- SNR 99 dB at full power (A-weighted); THD below 0.012%, THD+N below 0.02% (1 kHz, 1 W into 4 Ohm); damping factor 70; frequency response 10 Hz–20 kHz
- Fusing 2 x 30 A LP-Mini (APS); max. 70 A at 12 V DC; idle current 1,100 mA
DSP & Sound Tuning
- Analog active crossover (no DSP): high-pass 45–400 Hz, 12 dB/oct, can be turned off
- Low-pass 45–400 Hz, 12 dB/oct, can be turned off
- DirectDSP function to bypass the crossover when fed by an external DSP
Installation & Connectivity Notes
- Operating voltage 10.5–16 V (max. 5 s down to 6 V), start-stop capable
- Supported setups: active front (separate tweeter/woofer channels), passive front + rear, front + subwoofer on bridged channels
- Operating temperature range −40 °C to +70 °C
Technical Specifications
| Power RMS ≤ 1% THD+N @ 14.4 V | |
| – @ 4 Ohms | 4 x 100 Watts |
| – @ 2 Ohms | 4 x 190 Watts |
| – @ 1 Ohm | – |
| – bridged @ 4 Ohms | 2 x 380 Watts |
| – bridged @ 2 Ohms | – |
| Max. output power per channel* | Up to 240 Watts RMS @ 2 Ohms Up to 480 Watts RMS @ 4 Ohms bridged |
| Amplifier technology | Class D |
| Inputs | 4 x RCA / Cinch or 4 x Highlevel speaker input 1 x Remote In |
| Input sensitivity | RCA / Cinch: 1 – 8 Volts Highlevel: 2 – 16 Volts |
| Input impedance | RCA / Cinch: 8 kOhms Highlevel: 9 – 33 Ohms |
| Outputs | 4 x Speaker output |
| Output voltage RCA / Cinch | – |
| Signal converter for digital input | – |
| Frequency response | 10 Hz – 20.000 Hz |
| Bass boost | – |
| Highpass | 45 Hz – 400 Hz adjustable (can be turned off) |
| Lowpass | 45 Hz – 400 Hz adjustable (can be turned off) |
| Bandpass | – |
| Subsonic | – |
| Phase | – |
| Slope high- / lowpass | Highpass: 12 dB/Oct. Lowpass: 12 dB/Oct. |
| Slope subsonic | – |
| Slope subsonic / lowpass | – |
| Signal-to-noise ratio (A-weighted) | 99 dB @ full power |
| Distortion (THD @ 1 kHz, 1 W into 4 Ohms) | < 0.012% |
| Distortion (THD+N @ 1 kHz, 1 W into 4 Ohms) | < 0.02 % |
| Distortion (THD @ 100 Hz, 1 W into 4 Ohms) | – |
| Distortion (THD+N @ 100 Hz, 1 W into 4 Ohms) | – |
| Damping factor | 70 |
| Operating voltage | 10.5 – 16 Volts (max. 5 sec. down to 6 Volts) |
| Idle current | 1,100 mA |
| Fuse | 2 x 30 A LP-Mini-fuse (APS) |
| Power rating | DC 12 V ⎓ 70 A max. |
| Operating temperature range | -40 °C to +70 °C |
| Additional features | Active, adjustable crossover, input mode switch, Start-Stop capability, highlevel input with automatic turn-on function, ADEP.3, DirectDSP function |
| Dimensions (H x W x D) | 41.5 x 248 x 118 mm / 1.63 x 9.76 x 4.65” |
* One channel driven (≤ 10 % THD+N @ 14.4 V)
Scope of Delivery
1 x Amplifier HELIX AMPLIFY 204 X-OVER
2 x Allen key
3 x Connection cable
2 x Fuse
1 x Mounting material
1 x Instruction manual
